and works fine when I run the plugin from it's eclipse project (debug or run, both work fine) but if I then export the plugin and run eclipse (loading the exported plugin) my label provider does not appear to get loaded. I've added the logging of messages to the error log, and these messages (such as the creation of the label provider) only appear when the plugin is debugged/run from it's eclipse project.

This leads me to conclude that for some reason, the org.eclipse.dltk.ui.modelLabelProvider extension in the exported project is not being loaded. If I unzip the plugin jar file, everything appears to be intact.